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    <title>Document</title>
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<body>

    <script>
        const arr = [
            { id: 1, name: '西瓜', state: true, price: 10, count: 1 },
            { id: 2, name: '榴莲', state: false, price: 80, count: 2 },
            { id: 3, name: '草莓', state: true, price: 20, count: 3 }
        ]

        // 把购物车已勾选的水果总价累加起来
        let amt = 0
        arr.filter(item => item.state).forEach(item => {
            amt += item.price * item.count
        })
        console.log(amt)

        const res = arr.filter(item => item.state).reduce((amt, item) => amt += item.price * item.count, 0)
        console.log(res)
    </script>

</body>
</html>